啥话不说。。。
1 <?php 2 function setheight($height=50){ 3 echo "这个高度是 $height <br />"; 4 } 5 setheight(100); 6 setheight(); 7 ?>
<script> function setwidth(width){ width = width||500; alert(width) } setwidth(200); setwidth(152); setwidth(); </script>
原文：http://www.cnblogs.com/yyanga/p/4007974.html